The present invention relates to an electro-optical fuze that features range control by time-gating rather than by target rejection based on amplitude.
In proximity fuze systems presently in use on certain guided missiles, the time delay between the detection of the target and the warhead burst is programmed as a function of relative closing velocity between the target and the missile. The purpose of the delay is to maximize the probability of the lethal portions of the warhead striking a vulnerable area of the target. If correctly determined, this delay would be a function not only of closing velocity as in present systems, but also of missile-target range at time of detection by the fuze. Since present proximity fuze systems do not determine missile-target range at intercept, the time delay between target detection and warhead burst is of necessity a compromise based only on velocity information provided in most cases by the missile guidance system.
Other inventions provide a means of determining the missile-target range at the time of intercept, permitting a more optimum control over warhead burst time to effect maximum target damage.
One of the inventions of the latter type provides a circuit arrangement which permits the use of multiple range gates and special adapted thresholds which permit sharp range definition, resulting in the determination of target range at the time of target detection. The input from a receiver consisting of a unipolar video pulse train resulting from the detection of microwave pulses reflected from a target, is applied to the inputs of three gates and an amplitude detector. The timing of the gates is such that the pulses pass through target gate one if they have been reflected from an object, the range of which is between O and R1 feet. Pulses are passed through target gate two if they have been reflected from an object, the range of which is between R1 and R2 feet. In a similar manner, pulses are passed through target gate three if they have been reflected from an object, the range of which is between R2 and R3 feet. An amplitude detector and threshold driver set the thresholds on an individual pulse basis, thereby providing sharp discrimination between ranges regardless of pulse amplitude. Thus, such earlier invention provided a means of determining the missile-to-target range at the time of intercept, to permit a more optimum control over warhead burst time to effect maximum target damage.
It was in an effort to decrease the complexity of such prior art devices that the present invention was evolved.